HOESE: GOBIOIDEI 



591 



desmid-gobiid line (or lines) evolved, some genera, such as the 

 Gobiomorphus-Leptophilypnus group, may have evolved from 

 a common ancestor of the line (or lines). 



Irrespective of the number of families, or subfamilies of go- 

 bioid fishes recognized, there is no obvious evidence to combine 

 the 40 eleotridid genera with any particular gobioid group. It is 



clear that the interrelationships of this large group will not be 

 fully clarified in the near future. 



The Australian Museum, 6-8 College Street, Sydney 2000, 

 Australia. 



Scombroidei: Development and Relationships 



B. B. COLLETTE, T. POTTHOFF, W. J. RICHARDS, S. UeVANAGI, 

 J. L. RUSSO AND Y. NlSHIKAWA 



THE Scombroidei is a suborder of the Perciformes containing 

 6 families, 44 genera, and nearly 100 species. All species 

 are marine although at least one (Scomheromonts sinensis) moves 

 fairly long distances into fresh water. Most species are pelagic, 

 some epipelagic and some bathypelagic. 



The first modem definition of the scombroid fishes as the 

 suborder Scombroidei was by Regan (1909). He clearly sepa- 

 rated the scombroids from such percoid families as the Car- 

 angidae, Rachycentridae, Coryphaenidae, Bramidae, and Men- 

 idae. Within the Scombroidei, Regan recognized four divisions: 

 I. Trichiuriformes (Gempylidae and Trichiuridae); II. Scom- 

 briformes (Scombridae); III. Luvariformes (Luvaridae); and IV. 

 Xiphiiformes (Istiophoridae, Xiphiidae, and three families 

 known only as fossils). Regan's Scombroidei was defined by 

 three primary characters: premaxillae beak-like, gill membranes 

 free from the isthmus, and epiotics separated by the supraoc- 

 cipital. To include Luvarus in the Scombroidei, reversals must 

 be postulated in these three characters. The relationships of 

 Luvarus lie with the Acanthuroidei (Regan, 1 902; Leis and Rich- 

 ards, this volume; Tyler et al., MS) and will not be considered 

 here. Recent workers have usually recognized a suborder Scom- 

 broidei that is essentially the same as that of Regan (1909) 

 including the Luvaridae (e.g.. Greenwood et al., 1966) or have 

 placed the billfishes (Istiophoridae and Xiphiidae), along with 

 the Luvaridae, in a separate suborder, the Xiphioidei (Gosline, 

 1968; Potthoff et al., 1980), or have removed Xiphias from the 

 group and placed it in its own suborder, Xiphioidei (Potthoff 

 and Kelley, 1982). 



Scombroidei 



Perciform fishes with epiotics separated by the supraoccipital, 

 gill membranes free from the isthmus, premaxillae beak-like, 

 upper jaw nonprotrusile (except in Scombrolabrax), predorsal 

 bones lost (except for a small one in Ruvettus, Thyrsites, and 

 Tongaichlhys and three well-developed ones in Gasterochisma). 

 second epibranchial extending over the top of the third infra- 

 pharyngobranchial (except in Gasterochisma), vertebrae 24 or 

 more, inlerorbital commissure of the supraorbital canals widely 

 incomplete or absent (Regan, 1909; Gosline, 1968; G. D. John- 

 son, pers. comm.). 



Six families are recognized: Scombrolabracidae (monotypic; 

 Potthoff et al., 1980); Gempylidae (15 genera, 16 species; Mat- 

 subara and Iwai, 1952, 1958; Russo, 1983); Trichiuridae (9 

 genera, about 20 species; Parin and Bekker, 1972); Xiphiidae 



(monotypic); Istiophoridae (3 genera, about 1 1 species; Naka- 

 muraetal., 1968; Morrow and Harbo, 1969; Nakamura, 1974); 

 and Scombridae (15 genera, 49 species; Collette, 1979, 1983). 

 Fig. 3 1 2 is a Wagner Tree based on 40 characters considered 

 significant in assessing scombroid relationships (see Appendix) 

 generated by the computer program (WAGNER 78) written by 

 J. S. Farris (following Farris, 1970; Farris et al., 1970). The tree 

 is rooted at Scombrolabrax which is considered as the most 

 primitive scombroid and was used as the outgroup for com- 

 parison with the other scombroid fishes. Numbers show where 

 a character changes from a plesiomorphous {Scombrolabrax 

 condition) to a derived-apomorphous state. The gempylids were 

 grouped together on this cladogram because data were not avail- 

 able on all the characters. The unresolved areas have been re- 

 solved in a separate study by Russo (1983) and are discussed 

 in the section on the Gempylidae. The cladogram shows several 

 synapomorphies of the billfishes and the Scombridae: pharyn- 

 geal tooth plate stay (character 3; G. D. Johnson, pers. comm.), 

 pair of small lateral keels at the base of the caudal fin (character 

 12), caudal fin rays covering hypural plate (character 14), etc. 

 Billfishes show many character reversals and independent ac- 

 quisitions. Within the Scombridae, most groups seem well-de- 

 fined. 



Scombrolabracidae 



From its original description by Roule ( 1 922), Scombrolabrax 

 heterolepis has been considered as related to gempylid fishes 

 (Grey, 1960; Gosline, 1968; Potthoff et al., 1980). In most in- 

 stances wherein Scombrolabrax differs from the gempylids it 

 differs in the direction of the percoids: upper jaw protrusile, 

 some opercular bones spinous or serrate, pelvic girdle relatively 

 strong and attached to the cleithra, no fusion in the caudal 

 skeleton, one fewer vertebra (17 + 13 = 30) than in any other 

 scombroid (except the billfishes) and procurrent spur present 

 but reduced (Gosline, 1968; Johnson, 1975; Potthoff etal., 1980). 

 The stay on the pharyngobranchial of the fourth gill arch that 

 is present in the Scombridae, Xiphiidae, and Istiophoridae is 

 absent as in the Gempylidae and Trichiuridae (Potthoff et al., 

 1980). Roule (1922) originally placed Scombrolabrax in a sep- 

 arate suborder. Bond and Uyeno (1981) also recognized a sub- 

 order Scombrolabracoidei because of the unique specialization 

 in adults of the 5th through 12th vertebrae which are expanded 

 to form thin-walled bullae with wide ventral openings which 

 accommodate delicate bubble-like evaginations of the gas blad- 



